| Project/Area Number |
10354003
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Graduate School of Science, Nagoya University |
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Principal Investigator |
NAKANISHI Tutomu Nagoya Univ., Graduate School of Science, Professor, 大学院・理学研究科, 教授 (40022735)
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| Co-Investigator(Kenkyū-buntansha) |
HORINAKA Hiromichi Osaka Prefecture Univ., College of Engineering, Professor, 工学部, 教授 (60137239)
YOSHIOKA Masakazu KEK, Accelerator Laboratory, Professor, 加速器研究施設, 教授 (50107463)
KOBAYAKAWA Hisashi Nagoya Univ., Graduate School of Engineer, Professor, 大学院・工学研究科, 教授 (50022611)
BABA Simio NEC, Fundamental Research Laboratory, Research Director, 研究部長
SAKA Takashi Daido Institute of Technology, Dept. of Engineering, Professor, 工学部, 教授
加藤 俊宏 大同特殊鋼, 技術開発研究所, 主任研究員
馬場 寿夫 NEC(株), 基礎研究所, 研究部長
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥33,200,000 (Direct Cost: ¥33,200,000)
Fiscal Year 2000: ¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 1999: ¥8,800,000 (Direct Cost: ¥8,800,000)
Fiscal Year 1998: ¥19,000,000 (Direct Cost: ¥19,000,000)
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| Keywords | Spin / Polarization / Polarized Electron Source / Superlattice Semiconductor / Laser / Photocathode / Mulch-hunch Beam / Linear Collider / 偏極電子 / 電子銃 / 暗電流 / NEA / レーザー / 超格子 / 偏極電子源 / 超格子構造半導体 / レーザー励起 |
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| Research Abstract |
We developed polarized-electron-sources to produce an intense beam with a multi-bunch structure (2x10^<10>electrons/bunch, 100bunches, 2.8ns separation) for future linear colliders, such as Japan Linear Collider (JLC).
1 ) Polarized Electron Beam with Sub-ns Multi-bunch Structure
The NBA (Negative-Electron-Affinity) surface is indispensable to allow polarized electrons inside GaAs to emit into vacuum. However, it brings the serious problem due to photo-voltage effect that occurs when high-density electrons are excited by the first-laser-bunch and accumulated in NBA surface. Then the band-bending of GaAs surface is declined and then the electron emission by the second-laser bunch is strongly suppressed. We could find that the photo-voltage effect can be relaxed using the photocathode with a superlattice structure instead of the strained GaAs, and could demonstrate the clean double-bunch beam can be produced by GaAs-GaAsP or InGaAs-AlGaAs photocathode. The important problem is solved to produce the polarized multi-bunch beam for JLC by this work.
2 ) Development High-Gradient Polarized Gun
The next important subject is to produce the low emittance (【less than or equal】10πmm -mrad) beam by developing a gun with highergradient field (【greater than or equal】1MV/m) at GaAs surface. We constructed a new gun and succeeded to apply 200kV to electrodes with a small dark current (【less than or equal】1nA), which is much higher than 120kV achieved by SLAC-gun. We could obtain the high quantum efficiency by cleaning the GaAs surface by atomic hydrogen. We also pursued to produce a low emittance beam by an RF-gun. The two-photon-excitation method was proposed by us to solve a serious problem of survivability of NBA surface under high gradient field of 100MV/m. We could already confirm that the high polarization of 90% can be obtained by this method.
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